The false positive troponin results: case studies of analytical interference.

Cardiac troponin I and T are particularly sensitive and specific markers for cardiomyocyte damage. Myocardial injury can occur due to a discrepancy between oxygen supply and demand (eg coronary artery occlusion and arrhythmias), other cardiac causes (eg pericarditis, myocarditis, cardiac surgery, cardioversion etc) or systemic conditions (eg sepsis, stroke and chronic renal disease). The latest European Society of Cardiology guidelines help to guide clinicians through these different causes. Occasionally troponin concentrations may not fit the clinical presentation and, therefore, other aetiologies should be considered. An under-appreciated basis of a high troponin concentration is a false positive result, which can be attributable to analytical interference from components in the patient's blood. Uncovering this interference can be pivotal to avoid unnecessary and potentially harmful investigations or treatment for patients. We present two cases of false positive troponin results caused by analytical interference. The normal reference range for the assay (Access; Beckman Coulter, High Wycombe, UK) used at our organisation is 0-18 ng/L.

Risks of the 'Sunshine pill' - a case of hypervitaminosis D.

Vitamin D is a fat-soluble vitamin essential for calcium homeostasis and bone health. Vitamin D toxicity or hypervitaminosis D is extremely rare. We describe the case of a 73-year-old man who presented with life-threatening hypervitaminosis D and hypercalcaemia resulting from self-medicated doses of vitamin D supplements. This case, alongside other global case reports, highlights the potential dangers of unlicensed vitamin D replacement. We discuss the evidence for vitamin D replacement and remind readers of the current guidance on daily intake and supplementation.

The intercellular adhesion molecule, cadherin-10, is a marker for human prostate luminal epithelial cells that is not expressed in prostate cancer.

During the normal turnover of prostate epithelium, stem cells in the basal cell layer produce an intermediate cell population that gives rise to fully differentiated secretory luminal cells. This process is extensively studied in relation to the development of prostate disease, in particular, to elucidate the origin and nature of prostate cancer. We previously showed that the mRNA of a poorly characterised intercellular adhesion molecule, cadherin-10, is strongly expressed in human prostate. Using anticadherin-10 antibodies, immunohistochemistry, and confocal microscopy, we have examined the pattern of cadherin-10 expression in relation to human prostate epithelial differentiation markers (E-cadherin, CD44, and cytokeratins (CK) 14, 18 and 19) in archival paraffin-embedded and fixed-frozen histopathological specimens in individual and serial sections. In non-neoplastic prostate, E-cadherin is expressed by all basal and luminal epithelial cells, while cadherin-10 is variably expressed in luminal cells where it is colocalised with E-cadherin at basolateral plasma membranes. Cadherin-10 is absent in CK14- and/or CD44-positive basal cells, but is expressed in CK18-positive luminal cells (differentiated secretory cells), a subset of CK19-positive intermediate/luminal cells, but not CK19-positive basal cells. Small foci of prostate cancer express E-cadherin, CK19 and CK18, but cadherin-10 expression is low or undetectable. These findings suggest that the expression of cadherin-10 is associated with the later stages of differentiation of luminal secretory cells, indicating a specific role in secretory cell terminal differentiation. While prostate cancer cells express secretory cell markers (eg, CK18, prostate-specific antigen) and the more generally expressed E-cadherin, their failure to express cadherin-10 further emphasises a role for this cadherin in normal prostate organisation and function.